1. Field of the Invention
The present invention relates to a hand tool and, more particularly, to a combination wrench.
2. Description of the Related Art
A conventional combination wrench 1 in accordance with the prior art shown in FIGS. 1-4 comprises a shank 13, a first driving member 11 mounted on a first end of the shank 13, and a second driving member 12 mounted on a second end of the shank 13. The first driving member 11 is an open-ended spanner, and the second driving member 12 is a box-shaped spanner. The first driving member 11 and the second driving member 12 are disposed at the same plane. In operation, when the first driving member 11 or the second driving member 12 is used to operate a workpiece, such as a bolt, nut and the like, the reaction force is concentrated on the mediate portion of the shank 13. However, the shank 13 has a constant cross-sectional profile with a constant thickness as shown in FIGS. 2-4, so that when the reaction force is concentrated on the mediate portion of the shank 13, the mediate portion of the shank 13 easily produces a stress concentration, thereby distorting or breaking the shank 13 due to an excessive force.